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Physics
WAEC / WASSCE 2004
Atomic, Quantum, Nuclear Physics & Electronics
Solution
A radioactive substance has a half-life of 3 days. If a mass of 1.55g of this substance is left after decaying for 15 days, determine the original value of the mass
A
49.6g
B
37.2g
C
24.8g
D
12.4g
medium Difficulty
Verified Correct Answer: Option A
Physical Principles & Numerical Solution
\(1 \to \frac{1}{2} \to \frac{1}{4} \to \frac{1}{8} \to \frac{1}{16} \to \frac{1}{32}\)
\(\frac{1}{32} = 1.55g\)
1 = 1.55 x \(\frac{32}{1} = 49.6g\)
Source: Myschool Past Questions Archive (Record #34411)
Physics
WAEC / WASSCE 2004
Current Electricity & Electric Circuits
Solution
Which of the following representations is correct for an atom X with 28 electrons and 30 neutrons?
A
\(^{30}_{28} X\)
B
\(^{28}_{30} X\)
C
\(^{58}_{30} X\)
D
\(^{58}_{28} X\)
medium Difficulty
Verified Correct Answer: Option D
Physical Principles & Numerical Solution
\(X^{A = p + n = 28 + 30 = 58}_{Z = P = E = 28}\)
Source: Myschool Past Questions Archive (Record #34412)
Physics
WAEC / WASSCE 2004
Lenses & Optical Instruments
Diagram
In an experiment using a converging lens to produce real images on a screen, the linear magnification m, is plotted against the image distance v, as illustrated in the diagram below. The distance OP represents the
Attached Figure / Diagram
A
focal legth of the lens
B
thickness of the lens
C
radius of curvature of the lens
D
diameter of the lens
medium Difficulty
Verified Correct Answer: Option C
Physical Principles & Numerical Solution
No expanded working has been attached for this question yet. The verified answer is Option C.
Source: Myschool Past Questions Archive (Record #34413)
Physics
WAEC / WASSCE 2004
Current Electricity & Electric Circuits
Solution
Measure and record the emf, \(V_o\) of the cell provided.
Connect a circuit as shown in the diagram above.
With the key, K closed vary the rheostat, Rh to obtain a current 1 = 0.20A. Read and record the corresponding value of the potential difference, V on the voltmeter.
Evaluate 1\(^{-1}\) and V\(^{-1}\).
Repeat the procedure for four other values of l = 0.25, 0.30, 0.35 and 0.40 A. Tabulate your readings.
Plot a graph V\(^{-1}\) on the vertical axis against 1\(^{-1}\) on the horizontal axis.
Determine the slope, s, of the graph
Evaluate s\(^{-1}\).
State two precautions taken to ensure accurate results.
(b)i. Explain Ohmic conductor:
ii. Explain resistivity of the material of a wire.
A
focal legth of the lens
B
thickness of the lens
C
radius of curvature of the lens
D
diameter of the lens
medium Difficulty
Verified Correct Answer: Option C
Physical Principles & Numerical Solution
1. \(v_o\) = 3.0v
2. \(V_R\) = 0.20 volts
3. l = 0.20, 1\(^{-1}\) = \(\frac{1}{1} = \frac{1}{0.2}\) = 5
V = 0.2, V\(^{-1}\) = \(\frac{1}{V} =\frac{1}{0.2}\) = 5
Table of values/observations
S/N
IA
I\(^{-1}\)(A\(^{-1}\))
V(volts)
V\(^{-1}\)(volts\(^{-1}\))
1
0.20
5.00
0.19
5.26
2
0.25
4.00
0.23
4.35
3
0.30
3.33
0.28
3.57
4
0.35
2.86
0.33
3.03
5
0.40
2.50
0..38
2.63
Slope (s) = \(\frac{\bigtriangleup {V}^{-1}}{\bigtriangleup {I}^{-1}}\)
S = \(\frac{5.1-1.0}{4.55-12} = \frac{4.1}{3.35}\) = 1.224
S\(^{-1}\) = \(\frac{1}{s} = \frac{1}{1.224}\) = 0.817
N.B: R = S\(^{-1}\) = 1.0
Precautions taken to ensure accurate results are as follows
Tight connections ensured/clean terminals
Repeated readings have been shown on the table
Parallax error in reading voltmeter/ammeter avoided
Key open when reading is not being taken
(b)i. An ohmic conductor is s Conductor in which the current passing through it is proportional to the p.d across the conductor, provided temperature and other physical conditions are constant.
ii. The resistivity of the material of a wire is the resistance of a unit length of the wire of unit Crofs sectional area. It is denoted by p. and measured in ohm-metre (L-m).
Source: Official Exam / Past Question Archive
Physics
UTME / JAMB 2004
Reflection, Refraction & Dispersion of Light
Solution
Calculate the angle of minimum deviation for a ray which is refracted through an equiangular prism of refractive index 1.4
A
600
B
290
C
990
D
900
medium Difficulty
Verified Correct Answer: Option B
Physical Principles & Numerical Solution
From the relation refractive index(n) = \(\frac{sin(\frac{ A + Dm}{2})}{sin(\frac{A}{2})}\)
1.4 = \(\frac{sin(\frac{ 60º + Dm)}{2}}{sin(\frac{60}{2})}\)
1.4 = \(\frac{sin(\frac{ 60 + Dm}{2})}{sin30}\)
sin\(\frac{ 60 + Dm}{2}\) = sin 30 x 1.4
sin\(\frac{ 60 + Dm}{2}\) = 0.7
\(\frac{60 + Dm}{2}\) = sin\(^{-1}\)(0.7) = 44.427º
60 + Dm = 2 x 44.427 = 88.8
Dm = 88.8 - 60 = 28.8º ≈ 29º
Source: Myschool Past Questions Archive (Record #41445)
Physics
UTME / JAMB 2004
Current Electricity & Electric Circuits
Solution
A cell whose internal resistance is 0.5Ω delivers a current of 4A to an external resistor,The loss voltage of the cell is
A
1.250V
B
2.000V
C
8.000V
D
0.125V
medium Difficulty
Verified Correct Answer: Option B
Physical Principles & Numerical Solution
E = V + v
where E = emf of cell.
V = terminal p.d
v = loss voltage of the cell.
But from ohm's law V=IR ; v = Iv
\( \implies \) lost voltage = V = Ir
= 4 x 0.5
= 2.0v
Source: Myschool Past Questions Archive (Record #41446)
Physics
UTME / JAMB 2004
Elasticity, Density, Pressure & Fluids
Solution
If a force of 50N stretches a wire from 20m to 20.01m, what is the amount of force required to stretch the same material from 20m to 20.05m?
A
250N
B
200N
C
100N
D
50N
medium Difficulty
Verified Correct Answer: Option A
Physical Principles & Numerical Solution
Original length = 20m
first new length = 20.01m
first increase in length = 20.01m - 20m = 0.01m
Second new length = 20.05m
second increase in length = 20.05 - 20m = 0.05m
From hooke's law = \( \frac{F_1}{e_1} = \frac{F_2}{e_2}\)
\(\implies \frac{50}{0.01} = \frac{F_2}{0.05}\)
\(\implies F_2 = \frac{50 \times 0.05}{0.01} = 250N \)
Source: Myschool Past Questions Archive (Record #41447)
Physics
NECO SSCE 2004
Magnetism, Electromagnetism & AC Circuits
Which of these expresses the relationship between the earth’s magnetic field FE, and the field’ FB due to a magnet at neutral points? FE is
A
equal and opposite to FB
B
equal to and in the same direction with FB
C
greater than and in the same direction with FB
D
greater than and opposite to FB
E
less than and opposite to FB
medium Difficulty
Verified Correct Answer: Option A
Physical Principles & Numerical Solution
No expanded working has been attached for this question yet. The verified answer is Option A.
Source: Myschool Past Questions Archive (Record #42951)
Physics
NECO SSCE 2004
Current Electricity & Electric Circuits
The general equation of a wave CANNOT be written as
A
y = A Sin [2 π (\(\frac{t}{T}\) ± Xλ)]
B
y = A Sin [wt ± kx]
C
y = A Sin [2 \(\frac{\pi}{\lambda}\) (vt ± x)]
D
y = A Sin [2π (ft ± \(\frac{X}{\lambda}\) )]
E
y = A Sin 2 π f(T ± \(\frac{X}{\lambda}\))]
medium Difficulty
Verified Correct Answer: Option E
Physical Principles & Numerical Solution
No expanded working has been attached for this question yet. The verified answer is Option E.
Source: Myschool Past Questions Archive (Record #42952)
Physics
NECO SSCE 2004
Magnetism, Electromagnetism & AC Circuits
A voltage supply of 12V r.m.s. and frequency 90Hz is connected to a 4 ω resistor. Calculate the peak value of the current
A
48.8 A
B
30.0 A
C
27.5 A
D
4.2 A
E
3.0A
medium Difficulty
Verified Correct Answer: Option D
Physical Principles & Numerical Solution
No expanded working has been attached for this question yet. The verified answer is Option D.
Source: Myschool Past Questions Archive (Record #42953)
Physics
NECO SSCE 2004
Newton's Laws, Momentum & Collisions
Which of the following conclusion(s) can be drawn from Newton’s second law of motion? Force is proportional to
I. the product of mass and acceleration
II. the product of mass and velocity
III. Impulse
A
I only
B
II only
C
III only
D
II and III only
E
I, II and III
medium Difficulty
Verified Correct Answer: Option E
Physical Principles & Numerical Solution
No expanded working has been attached for this question yet. The verified answer is Option E.
Source: Myschool Past Questions Archive (Record #42954)
Physics
NECO SSCE 2004
Waves, Sound & Vibrations
How far from a hill should a boy stand to hear the echo of his clap 1 .6s later? [Speed of sound in air is 340ms-1]
A
186m
B
272m
C
544m
D
1088m
E
2000m
medium Difficulty
Verified Correct Answer: Option B
Physical Principles & Numerical Solution
No expanded working has been attached for this question yet. The verified answer is Option B.
Source: Myschool Past Questions Archive (Record #42955)
Physics
NECO SSCE 2004
Current Electricity & Electric Circuits
Which of the statements about prism binoculars is/are correct? They
I. are a pair of two telescopes mounted side by side
II. reduce the optical path of the light ray from the objective to the eye piece
III, present inverted and diminished image to the viewer
IV. present erect and magnified image to the viewer.
A
I only
B
II only
C
I and II only
D
I, II and IV only
E
II, III and IV only
medium Difficulty
Verified Correct Answer: Option D
Physical Principles & Numerical Solution
No expanded working has been attached for this question yet. The verified answer is Option D.
Source: Myschool Past Questions Archive (Record #42956)
Physics
NECO SSCE 2004
Calorimetry, Latent Heat & Change of State
A body of mass 40g loses 80J of heat energy. If the specific heat capacity of the body is 400 Jkg-1, calculate the change in temperature of the body.
A
0.2K
B
0.4K
C
2.0K
D
5.0K
E
10.0K
medium Difficulty
Verified Correct Answer: Option D
Physical Principles & Numerical Solution
No expanded working has been attached for this question yet. The verified answer is Option D.
Source: Myschool Past Questions Archive (Record #42957)
Physics
NECO SSCE 2004
Magnetism, Electromagnetism & AC Circuits
In which of these fields are repulsive forces NOT experienced?
I. Magnetic field
II. Gravitational field
III. Electric field
A
I only
B
II only
C
III only
D
I and III only
E
II and III only
medium Difficulty
Verified Correct Answer: Option B
Physical Principles & Numerical Solution
No expanded working has been attached for this question yet. The verified answer is Option B.
Source: Myschool Past Questions Archive (Record #42959)